EASTERN BOX TURTLE ASSESSMENT revised March 31, 2000 Prepared by: Charles S. Todd Maine Department of Inland Fisheries and Wildlife Wildlife Division Wildlife Resource Assessment Section Endangered and Threatened Species Group EASTERN BOX TURTLE ASSESSMENT TABLE OF CONTENTS Page INTRODUCTION............................................................................................................. 3 NATURAL HISTORY....................................................................................................... 4 Description............................................................................................................ 4 Distribution............................................................................................................ 6 Taxonomy............................................................................................................. 6 Habitat, Diet, and Movements .............................................................................. 8 Winter Hibernation.............................................................................................. 11 Reproductive Ecology......................................................................................... 12 Survival and Longevity ....................................................................................... 14 MANAGEMENT ............................................................................................................ 15 Regulatory Authority ........................................................................................... 15 Past Goals and Objectives ................................................................................. 19 Past and Current Management........................................................................... 19 HABITAT ASSESSMENT.............................................................................................. 20 Historic Trends ................................................................................................... 20 Current Assessment ........................................................................................... 20 Projections.......................................................................................................... 21 POPULATION ASSESSMENT...................................................................................... 22 Historic Trends ................................................................................................... 22 Current Assessment ........................................................................................... 22 Projections.......................................................................................................... 25 Limiting Factors .................................................................................................. 25 USE AND DEMAND ASSESSMENT ............................................................................ 27 Historic Trends ................................................................................................... 27 Current Assessment ........................................................................................... 28 Projections.......................................................................................................... 29 SUMMARY AND CONCLUSIONS ................................................................................ 30 LITERATURE CITED .................................................................................................... 32 APPENDIX1. Table 1. Historic and recent records of box turtles in southern Maine, by county and township................................. 41 2 EASTERN BOX TURTLE ASSESSMENT INTRODUCTION Since 1968, the Maine Department of Inland Fisheries and Wildlife (MDIFW) has developed and refined wildlife species assessments to formulate management goals, objectives, and strategic plans. Assessments are based upon available information and the judgments of professional wildlife biologists responsible for individual species or groups of species. This document represents the first planning effort by MDIFW for eastern box turtles (Terrapene carolina carolina), a reptile designated an “endangered species” in Maine. Assessments provide the background for species planning initiatives. A “Natural History” section reviews biological characteristics of the species useful to understanding its status. The “Management” section recaps previous actions, strategic plans, relevant rules, and regulatory authority. Historic, current, and projected future conditions for the species are discussed individually for “Habitat,” “Population,” and “Use and Demand” analyses. The major points of an assessment appear in a “Summary and Conclusions.” Owing to the extreme scarcity of eastern box turtles in Maine and limited information about them, this assessment draws heavily on studies and insights from other regions. Mark McCollough prepared two earlier drafts of this assessment. 3 EASTERN BOX TURTLE ASSESSMENT NATURAL HISTORY Description The eastern box turtle is a small terrestrial turtle with a high-domed carapace and unique plastron (Figure 1). The carapace (top shell) has a slight median keel and is steeply sloped on the rear margin. It is brown-colored with variable yellow, orange, or olive patterns of radiating lines, spots, bars, or irregular blotches on each scute. An adult's carapace is 10 - 20 cm long (Smith 1961, Conant and Collins 1991). Maximum size is attained at ages between 12 - 20 years (Nichols 1939). Individuals from the North, especially New England, are larger than others (Milstead 1969, Klemens 1993). The plastron (bottom shell) is tan to dark brown and variably mottled with yellow. A strong hinge on the plastron between the abdominal and pectoral scutes enables it to shut tightly against the carapace after withdrawing legs, head, and tail. This response is common among wild turtles, but not those which are pets. It seals soft body parts from external threats, an adaptation which accounts for the common name “box turtle.” The skin of eastern box turtles is black to reddish-brown with yellow or orange spots and streaks. Head markings vary. The upper jaw has a terminal hook and usually lacks a notch. Sexual dimorphism is marked (Ernst and Barbour 1972, Conant and Collins 1991, Klemens 1993). Most adult males have red or orange eyes; concave plastron; short, stocky, and considerably curved hind feet; long, thick tails; and relatively greater shell width and height than females. Females generally have yellowish-brown eyes; a flat plastron; longer, more slender, and straighter hind legs; and a shorter, slighter tail with the anus located more anterior. Hatchlings lack bright coloration. 4 EASTERN BOX TURTLE ASSESSMENT Figure 1. An eastern box turtle (Terrapene carolina carolina). Figure 2. Range of the eastern box turtle (Terrapene carolina carolina, solid shading), other eastern box turtle subspecies (Terrapene carolina, crosshatched), and ornate box turtles (Terrapene ornata, hatched areas) across North America. 5 EASTERN BOX TURTLE ASSESSMENT Distribution Box turtles occur only in North America (Conant and Collins 1991). Collectively, the two species native to the United States (see “Taxonomy”) range from the Atlantic Ocean to the Rocky Mountains. The species addressed in this assessment, the eastern box turtle (Terrapene carolina), reaches its western limits and overlaps with a midwestern species, the ornate box turtle (Terrapene ornata) in Wisconsin, Illinois, Missouri, Kansas, Oklahoma, and Texas. Eastern box turtles are broadly distributed in the eastern and central U. S. from northern states nearly abutting the Canadian border southward to the Gulf coast and northern Mexico (Figure 2). The subspecies native to Maine, T. c. carolina, occurs broadly over the Atlantic seaboard from southern Maine to northern Florida. It ranges westward through Illinois, Kentucky, Tennessee, and Mississippi to the Mississippi River. A crucial perspective to Maine, its northern limits, are traditionally depicted as: southern Maine; southeastern portions of New Hampshire, Vermont, and New York; across most of Pennsylvania and Ohio; central Michigan; and extreme southeastern Wisconsin (Behler and King 1979). Three other subspecies of eastern box turtles live in the South or Midwest. Taxonomy Approximately 250 species of turtles and tortoises belong to 12 different families in the taxonomic order Testudines (Tyning 1990). Box turtles (genus Terrapene) are members of the family Emydidae which contains the largest number of living turtle species. Commonly called the family of freshwater and marsh turtles, its members occur on all continents except Australia and Antarctica (Carr 1952). This family is 6 EASTERN BOX TURTLE ASSESSMENT represented by 33 species in the U. S. and Canada (Collins 1997). All are aquatic or semiaquatic except for the two species of Terrapene. Although they resemble tortoises (family Testudinidae), box turtles have freestanding toes and some toe webbing: traits shared among all emydid turtles (Tyning 1990). The genus Terrapene occurs exclusively in North America. Phalangeal formulae distinguish species and subspecies of Terrapene (Baur 1891, 1893; Taylor 1895; Minx 1992). The two species living in the U. S. are visually distinct. The ornate box turtle, T. ornata, is identified by distinct, bright colors on a keelless, low, and flattened carapace. The carapace of an eastern box turtle, T. carolina, is keeled and high-arched. They may cross breed in areas of range